The present invention relates to a solid state pickup device and a method of manufacturing the device, and particularly relates to a solid state pickup device is of a solid-molded type in which the whole of the device is molded and a method of manufacturing the device of the type.
Although various kinds of the solid state pickup device is are well known, a charge coupled device (hereinafter, abbreviated as CCD) device is recently widely used. Therefore, the CCD device is hereinafter mentioned as the representative of the various solid state pickup devices. However, the present invention is applicable to all the solid state pickup devices.
As the representative of mold types of the CCD device, the following two examples are well known. One example is a hollow-molded CCD device such that the whole of the device is molded hollowly and that a space is left therein. The other example is a solid-molded CCD device such that the whole of the device is substantially molded solidly and that no space is left therein. A method of manufacturing the solid-molded CCD device is, for example, disclosed in Japanese Unexamined Patent Publication (JP-A) No. 271153/1992.
The above-mentioned conventional CCD devices have the following problems.
Firstly, a reflow-soldering process, that is generally used for automatic mounting used to mount electrical devices or devices on a printed circuit board, cannot be applied to the hollow-molded or the solid-molded CCD device when mounted on the printed circuit board. Therefore, the hollow-molded or the solid-molded CCD device must be mounted on the printed circuit board by handwork using a soldering iron or a spouting-solder.
The reason is as follows. The hollow-molded CCD device comprises a top plate glued on an upper end thereof by using adhesive. The adhesive is set or cured by photosetting (photocuring) by ultraviolet rays. The top plate is deformed between approximate 80 and 160.degree. C. The adhesive is spoiled approximately between approximate 100 and 120.degree. C. On the other hand, the CCD device must be heated between approximately 260 and 300.degree. C. at lowest when applied into the reflow-soldering process. Namely, the top plate and the adhesive are deformed and spoiled when the reflow-soldering process is applied to the hollow-molded CCD device. On the other hand, the solid-molded CCD device comprises a solid package and a CCD chip packaged in the solid package. The solid package is comparatively better in heat-resistance. Therefore, the solid-molded CCD device can resist or withstand the reflow-soldering process if the process is short in time. However, the solid package and the CCD chip are greatly different from each other in heat-expansion coefficient. This means that the solid package and a CCD chip are stressed on each other when the reflow-soldering process is applied to the solid-molded CCD device. Therefore, the solid package or the CCD chip is cracked and the CCD chip is deformed. In addition, a surface of the solid package is deteriorated in flatness. Consequently, the solid-molded CCD device is deteriorated in optical and electrical performances.
Secondary, it is difficult to reduce the hollow-molded CCD device in size. The reason is that the hollow-molded CCD device needs enough space around the CCD chip in the hollow package so that bonding-wires are arranged without contacting each other.